1. Field of the Invention
The present invention relates, generally, to chain-utilizing machinery. More particularly, the invention relates to automated packaging machinery which utilize chains in drive conveyors and other assemblies or mechanisms thereof. However, the invention also may be found to have utility in other applications.
2. Background Information
Endless means such as chains, belts, cables and ropes have many uses on machinery. For example, torque is transferred from one rotating element to another through endless means running on shafts, pulleys or sprockets. Processing conveyors often are driven by endless means and may have conveyor elements attached to the endless means. Endless means stretch with use over time, and proper tension must be maintained in the endless means for the machinery to properly operate. The invention is described with respect to a chain, specifically a chain-driven conveyor, but the invention is applicable to tensioning other endless means.
One type of machine which commonly uses chain driven conveyors is a packaging machine. In a typical packaging machine for placing groups of articles, such as bottles or cans, within individual cartons, the cartons are in a collapsed form, called a blank, at one end of the packaging machine. Articles to be packaged are also fed in mass into one end of the machine. The machine opens a carton blank, groups and positions articles to be placed in the carton; brings the group of articles and carton together; then closes and seals the carton, and dispenses it out the other end of the machine.
The continuous motion of all the articles, cartons, packaged articles and mechanisms of the packaging machine is synchronized by mechanical and electronic devices. One of the most common mechanical devices used is a continuous chain. A typical packaging machine will have a number of continuous chains each performing a different function, and each with different elements attached to it. Such elements include flight bars for separating articles into groups, conveyor members for moving articles, pop-up conveyor members for maintaining separation of grouped articles, lugs and carrier assemblies for moving cartons, and barrel cam cross loading mechanisms for pushing grouped articles into cartons. All of these chains must be maintained at the proper tension for the machine to properly function. As the machine is used over time, the pins and holes of the chain wear causing the chains to stretch and lose tension. Consequently, each chain must be periodically retensioned.
In the past, chain tensioning has been done manually using a wrench or lever turning a series of screws, shafts, or turnbuckles. The tension developed in the chain was subject to the skill of the person tensioning it, and often varied depending on the strength of the person making the adjustment and the size of the wrench used. Too high a tension creates unnecessary wear of the chain, and too low of a tension may allow too much movement of the chain and potential disaster if a chain were to come off a sprocket.
Despite the need in the art for a chain tensioning system which overcomes the disadvantages, shortcomings and limitations of the prior art, none insofar as is known has been developed. Accordingly, it is an object of the present invention to provide an improved chain tensioning system which more accurately controls the level of tension in a chain. It is a further object of this invention to provide a chain tensioning system which is less dependent on the skill of the person adjusting the tension to achieve the proper tension. It is a further object of this invention to provide a chain tensioning system which indicates when a chain has been stretched to its limit and prevents the machine from operating. It is a further object of this invention to provide a chain tensioning system which tensions a chain semi-automatically.